This type of tax code doesn't add tax to the transaction but tracks the accrued tax that you would owe for Use Tax. The sale tax reports will now include a section to break out purchases that you may owe Use Tax for.
When creating a tax code, you'll see a new tax type to selected for Use Tax. Enter the tax rate and choose a linked accrued liability account to track the Use Tax that will be owed to the state.
When paying your Sales & Use Tax to the appropriate state tax authority, you would create a Spend Money transaction applied against the linked accounted used for Accrued Use Tax.